1. Technical Field
This description pertains generally to estimation of tissue deformation, and more particularly to lung tissue deformation.
2. Background Discussion
In human lung dynamics, a good and precise estimation of lung deformation during breathing is critical for targeted radiation oncology. Specifically, knowledge of the lung and tumor deformation during respiration can improve the efficiency of the radiation therapy with reference to minimizing exposure to surrounding healthy tissue. For example, in radiation oncology, physical phantoms can be used as a treatment quality assurance (QA) tool for delivering a given radiotherapy treatment plan.
To date, there exists no physical lung phantom that both incorporates physically accurate material properties and attenuated X-ray beam sources X-ray attenuation similar to an actual lung anatomy.
Work has been done to determine the lung deformation during respiration. Some of these studies include the use of pure imaging methods, Inverse Deformation (ID) methods, and the coupling of imaging and inverse methods for estimation. However these experimental methods are purely image-based and so involve a lot of discrepancies. As a counterpart of measurement, numerical modeling to simulate flow and deformation in the lung of humans has been studied, ranging from fractal theory to macroscopic. Because of limitation of each method, it is difficult to obtain detailed information.
Accordingly, an object of the present description is physical phantom that incorporates both physically accurate material properties and tissue-equivalent radiological properties. Another object is a 4D imaging/treatment methodology incorporating a deformable phantom for performing QA analysis. Another object is a 3D bio-printing method to generate or “print” subject-specific phantoms that are not currently available. At least some of these objectives will be met in the description provided below.